DE202004021675U1 - Power supply circuits - Google Patents

Abstract

A photovoltaic integrated power conditioning circuit for providing power to an AC mains power supply line from a photovoltaic device, the integrated circuit comprising:
a DC power input to receive DC power from the photovoltaic device;
a first DC / DC power conversion stage coupled to the DC voltage input for converting a first DC voltage from the photovoltaic device to a second, higher DC voltage, the first DC / DC power conversion stage including a first plurality of power -MOSEFT facilities comprises;
a second DC / AC power conversion stage having an input coupled to an output of the first DC / DC power conversion stage to convert the second, higher DC voltage into an AC voltage for the AC grid power supply line, the second DC / AC power conversion stage comprises a second plurality of power semiconductor devices;
an AC voltage output coupled to an output of the second DC / AC power conversion stage;
a first driver circuit coupled to drive the first DC / DC power conversion stage; and
a second driver circuit coupled to drive the second DC / AC power conversion stage;
wherein the integrated circuit has a common substrate on which ...

Description

These The invention relates generally to power supply circuits and especially circuits to a mains supply, such as the Household network, from a photovoltaic device with power to supply.

It is known to provide an AC power supply of 110 volts or 230/240 volts from a photovoltaic device using an inverter circuit. A photovoltaic (PV) standard panel supplies about 20 volts DC, about 4.5 amps max, and this voltage must be stepped up and converted to AC power to provide a network output. This is generally accomplished using an inverter constructed of individual electronic devices to convert the low DC input voltage to a high AC output voltage. Alternatively, there may be an initial step to up-transform the DC voltage before converting it to an AC voltage. An implementation of such a basic arrangement using the Hitachi ECN 3067 integrated circuit and, optionally, the ST Microelectronics L298 integrated circuit is described in U.S. Patent No. 5,309,866 "Grid Connected PV Inverters using a Commercially Available Power IC", A. Mumtaz, NP van der Duijn Schouten, L. Chisenga, RA MacMahon and GAJ Amaratunga, presented in October 2002 at the PV in Europe conference in Rome, Italy ,

Further state of the art can be found in AU 58687 . US 6151234 . AU 2073800 . EP 1035640 . NL 1011483C . US 4626983 A . EP 0628901 A . US 6603672 B . JP 2002 354677 A and JP 4364378 A ,

In In practice, the power is supplied to a household network the need to compromise the quality of the delivered To keep performance in standard limits, typically through Be determined by the supervisory authorities. These can be overcurrent, Undervoltage and overvoltage, as well as underfrequency and overfrequency conditions. Recommendations for connecting photovoltaic generators up to 5 kVA can be found in the by the U. K. Electricity Association created Engineering Recommendation G77. It contains details about Isolation of a PV inverter from the mains if the operating voltage exceeds 230V + 10% (253V) or below - 10% (207V). The Operating frequency should not exceed 50 Hz + 1% (50.5 Hz) or below - 6% (47 Hz). DC current injection should be 5 mA do not exceed. A particularly important problem becomes called islanding - d. h., if the household supply is turned off or disconnected, for example, devices and / or maintenance personnel to protect, then the PV inverter needs also stop delivering power to the grid. According to the above-mentioned recommendations should the shutdown time for the PV inverter is less than 5 seconds.

The The present invention addresses problems associated with conditioning and controlling one of a photovoltaic device provided Mains supply, and especially the problem of islanding. According to a first aspect of the present invention therefore becomes a photovoltaic power conditioning circuit provided to power from a photovoltaic device to supply to an AC mains power supply line, wherein the circuit includes: a DC input to DC power from the to receive photovoltaic device; an AC output, the configured for direct connection to the AC mains power supply line is; a DC / AC converter connected to the DC input and the AC output is coupled to DC power from the photovoltaic device to Converting output to the power supply line into AC power; and an electronic controller connected directly to the power supply line is coupled to a voltage on the power supply line and measure a current in the supply line and the DC / AC converter taking into account the measurement control.

direct coupling of the electronic controller to the power supply line enables the monitoring of line conditions without the need to close them from a measurement, at an earlier point in the delivery of performance from the PV device to the grid. Such indirect measurements take the risk that an error is the correct one Operation of the photovoltaic power conditioning disturbs and in particular the risk of the above-mentioned islanding.

In a preferred embodiment, the grid power supply voltage can be measured by establishing a direct connection to each of the grid power supply lines and reducing the voltage to a level suitable for input to a controller, such as a microcontroller, using a voltage divider. The current in the mains power supply line can be advantageously measured by serially connecting a current sensitive resistor to one of the supply lines and measuring the voltage across that resistor again, preferably using a voltage divider at both ends of the current sensitive resistor, by the sensed voltages to reduce to levels which are suitable for input to a microcontroller.

The Circuit can with the typical mains voltages of 110 volts and 230/240 volts or to be used with other mains voltages, and It can also be used to provide a direct mains supply to provide a device, such as a television, although they are particularly suitable for power supply to the mains is.

In In a preferred embodiment, the controller is to do so configured, a first frequency for the measured mains voltage and to determine a second frequency of the measured mains current and the DC / AC converter taking into account a difference to control between these two frequencies. Professionals will be clear be that the frequency of the current and the frequency of the voltage in Generally not identical because of the presence of reactive Loads associated with the network itself.

The Presence of such difference of frequencies indicates that Power through both the photovoltaic power conditioning circuit as well as by another connected to the supply network Power source to a load on the utility power supply line is delivered. Conversely, if the two frequencies are substantially equal equal, this can indicate that power to the utility grid was taken away and that power supply from the photovoltaic Device should also be switched off, for example by Disconnecting the DC / AC converter from the AC output. It is not necessarily the case that where the two frequencies are similar are, power supplied only by the photovoltaic device becomes. Therefore, the controller is preferable as well configured to progressively operate an operating frequency of the DC / AC converter to change, for example, to reduce the frequency to change the AC output accordingly, which monitors can be monitored by monitoring the second frequency, d. H. the frequency of the output current coming from the circuit the network is delivered. Where this progressive change This causes the second frequency outside a border falls without the difference between the first and second frequencies exceeds a threshold, d. h., generally speaking, where the first frequency of the second frequency essentially follows when the first frequency changes This indicates that performance is more likely to be more photovoltaic Power conditioning circuit is supplied as from the utility grid and therefore, islanding of the circuit is generated should, for example, by disconnecting the DC / AC converter from the AC output.

In In a preferred embodiment, those described above electronic control functions implemented by a microcontroller, which is coupled to main memory and to program memory, wherein the program memory processor control code saves to the above to implement described controller functions.

In A preferred embodiment becomes a large one Part of the power conditioning circuit on a single implemented integrated circuit. More specifically, it includes DC / AC converter preferably a plurality of MOSFETs and an optional, but preferred, the DC / AC converter upstream DC / DC converter, a variety of IGBTs (bipolar transistors with integrated Gate). These can be collectively called power facilities be designated, d. H. Facilities involved in the management of performance involved in the PV power supply from the PV device are. Such devices require drivers, such as CMOS drivers, which are generally separate from the power devices. In the case of circuits that operate at relatively high voltages, is good insulation between the power facilities and theirs Drivers important. For high voltage power equipment Generally, SOI (silicon-on-insulator) technology is used vertically integrated devices (although also barrier isolation technology can be used). This leaves because of the underneath lying buried oxide layer (BOX) no integration of the power devices and drivers too, blocking the connection between the two becomes. In a preferred arrangement, therefore, the power devices the present circuit laterally-integrated devices such as lateral IGBTs and lateral power MOSFETs such as LDMOSFETs (lateral double-diffused MOSFETs) in either CMOS or DMOS technology. this makes possible the (CMOS) drivers, which preferably also level shift and time synchronization elements include being integrated on the same substrate like the power devices, optionally with additional Analog circuit arrangement such as operational amplifiers or power factor correction u. Ä.

In A preferred embodiment includes the circuit an interface for a rechargeable battery, to allow power from the PV device both on-line and for battery-operated devices is delivered. Preferably, this interface is behind a arranged so-called MPP (maximum power point) tracking circuit, which aims to keep the PV device at an efficient operating point to keep.

The devices described above Kings can be implemented using computer program code, for example on a carrier medium such as a disk or a programmed memory such as a read only memory (firmware) or on an optical or electrical signal carrier. Code for implementing the controller may alternatively include code for a hardware description language such as Verilog (trademark), VHDL or SystemC.

These and other aspects of the invention will now be further described exclusively with the help of examples, with reference to the attached drawings, in which:

1 shows a block diagram of a photovoltaic power supply system according to an embodiment of the present invention;

2a and 2 B a controller network interface or comparator and associated waveforms for the controller of 2a demonstrate;

3 shows a flowchart of an inverter workflow;

4 shows a flowchart of a network connection monitoring process;

5 a schematic diagram of a photovoltaic inverter for use with the system of 2 shows;

6 a half-bridge driver circuit for the inverter of 5 shows; and

7 shows a cross-sectional view of a lateral IGBT next to an NMOS device.

1 shows an overall block diagram of a grid connected photovoltaic inverter and battery controller. The photovoltaic module is in 1 as an object 1 shown connected to the DC / DC converter. The 5V rail for the microcontroller is powered up using the power supply ( 2 ), which takes the input directly from the photovoltaic module. The microcontroller is connected to the DC / DC converter 4 , the DC / AC converter 6 and the exit 7 connected. Depending on the controller at the point 7 Accordingly, it varies the control of the power conditioning blocks via control connections accordingly 4a and 6a , The illustrated configuration is also constructed to be a battery 3 to load, which is shown connected from the DC / DC converter block.

2a shows an example of an interface configuration from the microcontroller to the network. The figure shows how the PV inverter is connected to the grid and shows the configuration of the feedback to the inverter via the microcontroller. The microcontroller is used to monitor the power quality of the inverter and the network interface. This is done by monitoring and controlling the size, phase and frequency of both the current and the voltage at the connection point of the inverter and the network. The grid is a high voltage / power supply (typically 240V AC) or load, while the microcontroller is a low power device (typically 5V power supply).

R1 to R8 are potentiometer resistors. These are used to adjust the high line voltages. In one embodiment the upper resistors have values of 2 MΩ while the lower values of either 10kΩ or 40kΩ. Rc is a current sensing resistor, which in one embodiment has a value of about 2 Ω. D1 to D8 are Protection diodes. These diodes make sure that the connection point each pair of resistance no voltages above the reached above supply voltage. This results in, that the comparators C1, C2 and the microcontroller before the in the power lines, live and neutral, protected against high voltages and currents are. C1 and C2 also buffer the size and frequency of the current and voltage signals before the connection come with the microcontroller from the voltage dividers.

2 B shows details of a comparator and also input and output waveforms for comparators C1 and C2. The comparator has two inputs (- / +), inverting and non-inverting. Two resistors, one grounded in the feedback loop and the other grounded, are used to configure the comparator in an amplifier mode. The output is connected to a board-side microcontroller Schmitt trigger and an A / D converter. The two inputs to the comparator are differential and the resulting output from the comparator is no longer floating voltage but zero centered output voltage. For comparator C1, voltage is fed to the comparator from the live and neutral conductors which float and have a fixed 110V AC or 240V AC size difference. For comparator C2, the voltage difference is due to the voltage drop across resistor Rc. The frequency of the signals fed into the comparators is essentially the same for each case. This output is processed in two ways. It is sampled on the microcontroller using an A / D converter, allowing the frequency of the signals to be calculated. Same off Output from the comparator is also passed to a Schmitt trigger, whereby the size of the signals can be determined.

3 shows the operating procedure of the inverter before the mains connection. Before the inverter closes switches S1 and S2 (in 2a shown) is connected or reconnected, a number of conditions must be determined and then checked to see if they are within the required limits. The flowchart in 3 shows steps that are performed by the inverter before the connection. At the time of turning on the microcontroller (step 1 ), the inverter determines the frequency and voltage of the mains supply (step 2 ). If it appears that the frequency or voltage is outside the desired range (step 3 ), the inverter remains idle in idle mode. At fixed intervals, he checks the power supply (step 2 ) to determine if the supply has returned to normal. In the event the mains supply voltage and frequencies are determined to be desirable, the inverter then checks the DC link voltage to evaluate whether it is sufficient to activate the connection (step 4 ). If the DC link voltage is below the threshold, the inverter would step up the voltage until the threshold is reached (step 5 ). The DC link voltage can be varied in two ways. A multitag transformer or a variable duty cycle boost step-up circuit may be used. Once all conditions have been tested and fulfilled, switches S1 and S2 are closed, which is controlled by the microcontroller, and the inverter is connected to the grid (step 7 ). The system then proceeds to monitor its operation in the event of an abnormal condition and disconnects if such an abnormality persists. Some of the constantly monitored conditions will be discussed later (step 8th ).

4 Figure 11 shows the flowchart of the process steps involved in the monitoring process, allowing the system to disconnect if conditions occur which may adversely affect the operation of the overall system. Some of the abnormal conditions are described below. Once the inverter is connected, voltages, currents and their frequencies must be monitored (step 9 ). The frequencies are then compared to check if they are less than the required threshold (step 10 ). If so, the voltage is checked to determine if it is outside the required range (step 12 ); if yes, then the PV inverter is disconnected and returns to the sequence before the grid connection ( 3 ). If the current and voltage frequencies are not within the required threshold (step 10 ), then the current frequency is reduced (step 11 ) and then the voltage frequency is checked (step 12 ). If the voltage is within the range (step 12 ), then the current / voltage magnitudes are checked to see if they are in the required range (step 14 ). If not, the PV inverter is disconnected (step 13 ) and enters the process of 3 one. If the sizes are within the required range, then the PV inverter remains connected and cycles through the loop periodically.

Some the abnormal conditions that can occur in the system contain overcurrent, overvoltage, undervoltage, overfrequency, Underfrequency and islanding. The inverter temporarily disconnects if any of these conditions occur by following the above procedure used. The abnormal current, voltage or frequency conditions can result from a faulty condition in the system, an overload or underload. It is said that overcurrent occurs when more current than normal flows in the power lines. Undervoltage is a condition in which the line voltage is below the lower set threshold decreases. Overvoltage is a Condition in which the line voltage is set above the upper Threshold rises. It is said that overfrequency occurs when the line frequency exceeds the upper threshold. It is said that underfrequency occurs when the line frequency the lower threshold falls below.

5 shows a circuit configuration for the PV inverter. A standard PV panel feeds into the inverter. The microcontroller is not shown, but is compatible with the MPP (Maximum Power Point) tracking, battery interface, and driver circuits. The MPPT is a circuit configuration (known to those skilled in the art) that is controlled by the microcontroller to enable the maximum power from the photovoltaic module to be transferred to the inverter. Another circuit that is preferably inserted at this stage is the battery interface circuitry, which allows a standard battery to be charged by the module. The filter capacitor ensures a uniform supply to the lateral MOSFET full bridge. The lateral MOSFETs are switched at high frequency (30 kHz) to produce a square wave output. This is then up-converted by the high-frequency transformer to high voltage. The rectifier is used to generate a high voltage DC link connected to a PWM (pulse width modulated) switched lateral IGBT (insulated gate bipolar transistor) inverter. The generated output is the AC mains voltage. The sections of the circuit that are monolithically integrated on a single silicon chip are the high frequency full bridge MOSFETs, the rectifier stage, the IGBT lateral inverter stage and the associated driver circuits.

6 Figure 13 shows the driver circuit using a pulsed source circuit level shift scheme and a standard method of driving half-bridges. The low-side circuit converts the signal from the microcontroller into three signals. First, it generates the inversion of the input signal and inserts dead time between the two signals. The inversion is connected to the low-side power device. The actual input signal is then divided into a pulse with a rising edge and a pulse with a falling edge. These then switch the level shift MOSFETs LS and LR at the appropriate times. When this happens, a voltage is developed across the resistors Rs and Rr. This voltage triggers the high-side circuit, which consists of an input stage for rejecting spurious transients and an SR (set-reset) latch circuit. This generates the appropriate gating signal for the high-side device. In addition, since the high side is isolated, the high side circuit is allowed to float to the high side voltage. In addition, the high-side and low-side circuits contain MOS gate drivers, which consist of a string of CMOS inverters of specific sizes.

7 shows a cross-sectional view of a lateral IGBT next to an NMOS device. The PV inverter preferably comprises a monolithic circuit whose active components are made of a single semiconductor substrate. To integrate the lateral MOSFETs, LIGBTs and the high voltage rectifier stage, there are two main requirements: a suitable manufacturing process and an isolation process. Isolation is required so that the power devices do not interfere with each other and do not disturb the low-voltage CMOS devices. In 7 It can be seen that the insulation is provided by a vertical trench which extends down to the buried oxide. As those skilled in the art will appreciate, an appropriate manufacturing process can be established by optimizing a CMOS process to enable integration of all devices through routine but extensive computer simulations. In particular, the common layers such as p-well, n-well, and n-drift are preferably optimized to allow the devices to operate to a satisfactory degree.

Without Doubts will give professionals many other effective alternatives Conceive, and it should be clear that the invention is not limited to the embodiments described is.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - AU 58687 [0003]
• US 6151234 [0003]
• - AU 2073800 [0003]
• - EP 1035640 [0003]
• NL 1011483 C [0003]
• - US 4626983 A [0003]
• - EP 0628901 A [0003]
• - US 6603672 B [0003]
• - JP 2002354677 A [0003]
• - JP 4364378 A [0003]

Cited non-patent literature

• - "Grid Connected PV Inverters using a Commercially Available Power IC", A. Mumtaz, NP van der Duijn Schouten, L. Chisenga, RA MacMahon and GAJ Amaratunga, presented in October 2002 at the PV in Europe conference in Rome, Italy [0002 ]

Claims (12)

Photovoltaic integrated power conditioning circuit for providing power to an AC grid power supply line from a photovoltaic device, the integrated circuit includes: a DC power input to DC power from the to receive photovoltaic device; a first DC / DC power conversion stage, which is coupled to the DC voltage input, to a first DC voltage from the photovoltaic device into a second, higher Convert DC voltage, wherein the first DC / DC power conversion stage a first plurality of power MOSEFT devices; a second DC / AC power conversion stage with an input on coupled to an output of the first DC / DC power conversion stage is to turn the second, higher DC voltage into an AC voltage for the AC network power supply line, wherein the second DC / AC power conversion stage is a second plurality of power semiconductor devices; an AC voltage output, to an output of the second DC / AC power conversion stage is coupled; a first driver circuit that is docked is to drive the first DC / DC power conversion stage; and a second driver circuit coupled to the second DC / AC power conversion stage head for; wherein the integrated circuit is a common substrate On which are manufactured: the first DC / DC power conversion stage including the first plurality of power MOSFET devices, including the second DC / AC power conversion stage the second plurality of power semiconductor devices, the first driver circuit and the second driver circuit; wherein the integrated circuit has an integrated silicon-on-insulator circuit with a buried oxide layer, and wherein the first driver circuit and a part of the first DC / AC power conversion circuit unconnected are and from the second DC / AC power conversion circuit and the second driver circuit are electrically isolated, wherein the electrical insulation filled with a dielectric Includes digging on the integrated circuit that runs down, to contact the buried oxide layer. Photovoltaic integrated power conditioning circuit according to claim 1, wherein the second plurality of power semiconductor devices a plurality of bipolar power semiconductor devices and wherein the integrated circuit using a process is made for the production of a combination the power MOSFET devices and the bipolar power semiconductor devices is optimized. Photovoltaic integrated power conditioning circuit according to claim 2, wherein the plurality of power bipolar power semiconductor devices Variety of IGBTs. Photovoltaic integrated power conditioning circuit according to claim 2 or 3, wherein the power MOSFET devices and the bipolar power semiconductor devices include lateral bipolar power semiconductor devices include. Photovoltaic integrated power conditioning circuit according to any preceding claim, wherein the first DC / DC power conversion stage includes a transformer drive connection to an AC power output to provide a transformer, and a transformer input connection, to receive an AC power input from the transformer, wherein the first variety of power MOSFET devices between the DC power input and the transformer drive connection coupled is, and also comprising at least one rectifier, between the transformer input connection and the DC output the first DC / DC power conversion stage is coupled, and wherein the part of the first DC / DC power conversion circuit used by the second DC / AC power conversion stage electrically isolated is comprising the first plurality of MOSFET devices. Photovoltaic integrated power conditioning circuit according to claim 5, wherein the at least one rectifier is not of the second DC / AC power conversion stage electrically isolated is. Photovoltaic integrated power conditioning circuit according to any preceding claim, wherein the first driver circuit a voltage level shift circuit comprises at least to control one of the multitude of power MOSFET devices, and wherein the second driver circuit provided by the first driver circuit electrically insulated, is configured to at least one the second plurality of power semiconductor devices without such intermediate voltage level shift circuit head for. Photovoltaic integrated power conditioning circuit according to claim 7, wherein one or both of said first and second drive circuits comprise a string of CMOS inverters. Photovoltaic integrated Leistungsungskonditio nierungsschaltung for providing power to an AC mains power supply line from a photovoltaic device, the integrated circuit comprising: a DC power input to receive power from the photovoltaic device; a first DC / DC power conversion stage coupled to the DC voltage input for converting a first DC voltage from the photovoltaic device to a second, higher DC voltage, wherein the first DC / DC power conversion stage comprises a first plurality of lateral DC voltages Comprising power MOSEFT devices; a second DC / AC power conversion stage having an input coupled to an output of the first DC / DC power conversion stage to convert the second, higher DC voltage into an AC voltage for the AC grid power supply line, the second DC / AC power conversion stage comprises a second plurality of lateral bipolar power semiconductor devices; an AC voltage output coupled to an output of the second DC / AC power conversion stage; a first control input for receiving a first control signal from a controller; a first driver circuit coupled to the first control input and the first DC / DC power conversion stage, the first driver control circuit controlling the switching of the plurality of lateral power MOSFET devices in consideration of the first control signal from the controller; a second control input to receive a second control signal from the controller; and a second driver circuit coupled to drive the second control input and coupled to the second DC / AC power conversion stage, the second driver circuit controlling switching of the plurality of lateral bipolar power semiconductor devices in consideration of the second control signal from the controller; wherein the integrated circuit is a buried oxide layer integrated silicon-on-insulator circuit and wherein the first driver circuit and a portion of the first DC / AC power conversion circuit are unconnected and electrically connected by the second DC / AC power conversion circuit and the second driver circuit wherein the electrical insulation comprises a dielectric-filled trench on the integrated circuit that extends downwardly to contact the buried oxide layer. Photovoltaic integrated power conditioning circuit according to claim 9, wherein said plurality of bipolar semiconductor devices includes a variety of IGBTs. Photovoltaic integrated power conditioning circuit according to claim 9 or 10, wherein the first driver circuit comprises CMOS devices and a voltage level shift circuit for driving at least one of the plurality of lateral power MOSFET devices and wherein the second driver circuit, that of the first Driver circuit is electrically isolated, CMOS devices includes and configured to at least one of the second plurality of lateral bipolar power semiconductor devices without a to control the intermediate voltage level shift circuit. Photovoltaic integrated power conditioning circuit according to claim 9, 10 or 11, wherein the first DC / DC power conversion stage comprises a Transformer drive connection includes an AC power output to provide a transformer, and a transformer input connection, to receive an AC power input from the transformer, wherein the first plurality of lateral power MOSFET devices between the DC power input and the transformer drive connection is coupled, and also at least one rectifier comprising between the transformer input connection and the DC output coupled to the first DC / DC power conversion stage and wherein the part of the first DC / DC power conversion circuit, which is electrically isolated from the second DC / AC power conversion stage is the first variety of lateral power MOSFET devices includes.